Programmable bridging apparatus to connect multiple networks of different protocols

STATEMENT OF GOVERNMENT RIGHTS

This invention was made with government support under Contract No. F30602-95-C-0026 awarded by the U.S. Air Force. The Government has certain rights in this invention.

FIELD OF THE INVENTION

The present invention relates in general to communications systems and, more particularly, to communications systems that utilize signal bridging techniques.

BACKGROUND OF THE INVENTION

A bridge is a communications device for connecting two or more communications networks together to enable communication between the networks. In a typical bridge, a message is received from one of the connected networks and is delivered to one or more other networks via a bridge connection. Bridges do not normally choose a specific path within a destination network by which to deliver a message to a destination node, but instead “broadcast” the message to all nodes within the destination network. The destination node within the destination network, knowing its own address, then accepts the message from the broadcast medium.

In wireless applications, bridges can be used to connect two or more wireless communications networks. Normally, such bridges are implemented manually by an operator having enough analog equipment to support two or more external wireless communications channels. The operator determines which external networks are to be connected and configures the analog equipment to perform the desired bridging function. As can be appreciated, such bridges are very specialized and require a costly and time consuming redesign whenever system requirements change. In addition, these bridges are relatively slow, expensive to maintain, non-adaptable, and generally non-reliable. Further, these bridges do not generally provide interoperability between incompatible networks.

Therefore, there is a need for a bridge that can be easily adapted to changing system requirements. In addition, there is a need for a bridge that is capable of supporting networks utilizing different, and possibly varying, signal formats. Further, there is a need for a bridge that does not require manual setup by an operator. Still further, there is a need for a bridge that can fill the above needs in a wireless environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a bridging apparatus in accordance with one embodiment of the present invention;

FIG. 2 is a block diagram illustrating a software bridge in accordance with one embodiment of the present invention; and

FIG. 3 is a block diagram illustrating a bridging apparatus in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention relates to a bridging apparatus that satisfies the above-identified needs. The bridging apparatus includes a bridge that utilizes a digital processor for implementing a desired bridging function. The digital processor includes a memory for storing at least one bridging program for execution by the digital processor. A plurality of network interfaces are coupled to the bridge for providing an interface to a plurality of external communications networks. Each network interface is capable of converting between the signal format of an associated external network and a common signal format recognized by the bridge. The digital processor, while executing a bridging program, establishes at least one bridge connection between two or more of the external communications networks. In general, a particular bridge connection (or set of bridge connections) will be maintained until there is a change in system requirements (such as the need to add a new network to or remove an old network from the bridged connection). When such a change occurs, the bridging program can be modified or a new bridging program can be supplied to support the change.

Because the bridging apparatus converts all received signals to a common signal format, the apparatus is capable of providing interoperability between a plurality of previously incompatible networks. In addition, because the bridging function is implemented in software, the bridging apparatus is easily adapted to changing system requirements, rarely requiring expensive bridge redesigns and/or manual equipment reconfiguration. Furthermore, the bridging apparatus provides a high level of software-based control to a user for providing a wide range of bridging functions between networks. The bridging apparatus of the present invention is also highly reliable, easy to use, and cost effective. While having value in virtually any bridging application, the bridging apparatus of the present invention is of particular value in wireless applications.

As used herein, the term “signal format” refers to a unique combination of signal characteristics that distinguish one signal from another. In general, systems that utilize a particular signal format cannot recognize signals having other formats. In this regard, a signal format can include, for example, a designation of one or more of the following signal characteristics: waveform type (e.g., center frequency, modulation type, etc.), information type (e.g., voice, video, data, etc.), signal protocol, multiple access type (e.g., CDMA, TDMA, FDMA, etc.), signal encryption type, signal vocoder type, and others.

FIG. 1 is a block diagram illustrating a bridging apparatus <b>10</b> in accordance with one embodiment of the present invention. The bridging apparatus <b>10</b> is capable of providing bridging services between a plurality of external communications networks <b>20</b><i>a</i>-<b>20</b><i>n</i>. That is, the bridging apparatus <b>10</b> is operative for establishing bridging connections between the external networks <b>20</b><i>a</i>-<b>20</b><i>n </i>in accordance with system requirements. In addition, the bridging apparatus <b>10</b> is capable of interfacing with a user at user device <b>24</b> for establishing connections between the user and one or more of the external networks <b>20</b><i>a</i>-<b>20</b><i>n </i>or for receiving configuration commands from the user. It should be noted that the blocks illustrated in FIG. 1 represent functional elements that do not necessarily correspond to discrete hardware units. For example, in one embodiment of the present invention, all of the illustrated functionality is implemented within a single processor.

As illustrated in FIG. 1, the bridging apparatus <b>10</b> includes: a plurality of network interfaces <b>12</b>, a bridge <b>14</b>, and a user interface <b>16</b>. Preferably, the plurality of network interfaces <b>12</b>, the bridge <b>14</b>, and the user interface <b>16</b> are all located within a single support structure. The plurality of network interfaces <b>12</b> includes at least two interface functions for interfacing with external communications networks. During operation, each of the plurality of network interfaces <b>12</b> communicates with at least one of the external communications networks <b>20</b><i>a</i>-<b>20</b><i>n </i>via a corresponding communications channel. For example, in the illustrated embodiment, network interface <b>18</b><i>a </i>communicates with external network <b>20</b><i>a </i>via communications channel <b>22</b><i>a</i>; network interface <b>18</b><i>b </i>communicates with external network <b>20</b><i>b </i>via communications channel <b>22</b><i>b</i>; and network interface <b>18</b><i>n </i>communicates with external network <b>20</b><i>n </i>via communications channel <b>22</b><i>n</i>. The communications channels <b>22</b><i>a</i>-<b>22</b><i>n </i>can each include virtually any form of communications medium, either wired or wireless. Likewise, the external communications networks <b>20</b><i>a</i>-<b>20</b><i>n </i>can be either wired or wireless networks. In one embodiment of the invention, all of the communications channels <b>22</b><i>a</i>-<b>22</b><i>n </i>are wireless channels.

In accordance with the present invention, each of the network interfaces <b>18</b><i>a</i>-<b>18</b><i>n </i>is capable of converting communications signals between a signal format used by an associated external communications network and a common signal format supported by the bridge <b>14</b>. The individual network interfaces <b>18</b><i>a</i>-<b>18</b><i>n </i>can be implemented in hardware, software, or a hybrid hardware/software approach can be used. In addition, the network interfaces <b>18</b><i>a</i>-<b>18</b><i>n </i>can be implemented using analog processing, digital processing, or both analog and digital processing. In a preferred embodiment, the network interfaces <b>18</b><i>a</i>-<b>18</b><i>n </i>are each capable of performing any of the functions necessary to convert a signal received from an external communications network to the common signal format. Likewise, the network interfaces <b>18</b><i>a</i>-<b>18</b><i>n </i>are each capable of performing any of the functions necessary to convert a signal having the common signal format to an appropriate transmit signal format for delivery to an external communications network. In this regard, the network interfaces <b>18</b><i>a</i>-<b>18</b><i>n </i>can each include functionality for performing one or more of the following tasks: signal reception/transmission, signal upconversion/downconversion, signal amplification, signal modulation/demodulation, error correction coding/decoding, signal encryption/decryption, vocoder encoding/decoding, protocol conversion, and others. In one embodiment of the invention, as will be described in greater detail, each of the network interfaces <b>18</b><i>a</i>-<b>18</b><i>n </i>includes an individual radio channel adapted for use with a predetermined signal format.

The bridge <b>14</b> is operative for establishing at least one bridge connection between external communications networks. As used herein, the term “bridge connection” refers to a connection that allows information to flow from one of the external communications networks to any one or more of the other external communications networks via the bridge <b>14</b>. For example, a bridge connection can be established that always transfers signals received by network interface <b>18</b><i>b </i>(from external network <b>20</b><i>b</i>) to both external network <b>20</b><i>a </i>and external network <b>20</b><i>n</i>. Preferably, the signal transfer is automatic to support real-time communication between networks. In one implementation, bridge connections are established by the bridge <b>14</b> whereby signals received by any one of the plurality of network interfaces <b>12</b> are automatically transferred to all of the other network interfaces in the plurality <b>12</b> for delivery to corresponding external networks. As will be apparent to a person of ordinary skill in the art, many other connection configurations are also possible.

As described above, the user interface <b>16</b> provides an interface between the bridge <b>14</b> and the user device <b>24</b>. Among other things, the user interface <b>16</b> performs the required signal conversions needed for communication between the bridge <b>14</b> and the user device <b>24</b> to occur. As will be described in more detail, a user at user device <b>24</b> can deliver configuration commands to the bridge <b>14</b> over the user interface <b>16</b> instructing the bridge <b>14</b> to establish a particular bridge connection between external communications networks <b>20</b><i>a</i>-<b>20</b><i>n</i>. In addition, the user can deliver new or modified bridging programs to the bridge <b>14</b> via user interface <b>16</b>. In addition to these control-based functions, the user interface <b>16</b> can also be used as a communications medium for transferring communication signals between user device <b>24</b> and one or more of the external networks <b>20</b><i>a</i>-<b>20</b><i>n</i>. In one embodiment of the invention, for example, all communications signals received from any of the external communications networks <b>20</b><i>a</i>-<b>20</b><i>n </i>are automatically delivered to the user device <b>24</b> for consideration by the user. Similarly, all communications signals generated by the user can be delivered to all of the external communications networks <b>20</b><i>a</i>-<b>20</b><i>n</i>. Other user connections are also possible.

In accordance with the present invention, the functionality of the bridge <b>14</b> is implemented in software within a digital processor. The digital processor can include, for example, a general purpose microprocessor (GPP), a digital signal processor (DSP), a reduced instruction set computer (RISC), a complex instruction set computer (CISC), or any other type of digital processing device. In general, the digital processor will include a memory (such as a random access memory (RAM)) that is capable of storing one or more bridging routines. To establish one or more bridge connections, the digital processor executes a corresponding bridging routine stored in the memory.

It should be appreciated that the bridging apparatus of the present invention does necessarily convert all received signals to the common signal format for purposes of bridging the signals. For example, if two or more external networks that utilize the same signal format are being bridged, the signals can be directly bridged without conversion. In addition, if two or more external networks are being bridged that utilize some, but not all, of the same signal formatting (such as, for example, using different modulation types but the same voice coding type), received signals can be converted down to an intermediate signal format that is common to the two or more external networks before bridging. Intelligence can be provided within the bridge <b>14</b> for determining when one of the above arrangements can be performed.

FIG. 2 is a block diagram illustrating a bridge <b>14</b> in accordance with one embodiment of the present invention. As illustrated, the bridge <b>14</b> includes a processor <b>30</b> with associated RAM <b>32</b> and a hardware bus <b>34</b>. The processor <b>30</b> is coupled to a mass storage unit <b>38</b> located outside the bridge <b>14</b>. The processor <b>30</b>, the user interface <b>16</b>, and the plurality of network interfaces <b>12</b> are coupled to the hardware bus <b>34</b> for use in transferring information between the units. In a preferred embodiment, the various elements are connected to the hardware bus <b>34</b> via standard hardware interfaces, such as standard input/output (I/O) ports. In addition, further I/O ports can be provided for supporting, among other things, additional external communications networks in the future.

Using the hardware bus <b>34</b>, bridging commands and/or routines can be transferred from a user to the processor <b>30</b>. For example, in one scenario the user can instruct the processor <b>30</b> to execute a different bridging routine in the RAM <b>32</b> than it is currently executing. In another possible scenario, the user can instruct the processor <b>30</b> to download a bridging routine from the mass storage unit <b>38</b> to the RAM <b>32</b> for execution. In yet another possible scenario, the user can deliver a new bridging routine to the processor <b>30</b> for storage in the RAM <b>32</b> and/or the mass storage unit <b>38</b> via hardware bus <b>34</b>. Hardware bus <b>34</b>, under the control of the processor <b>30</b>, is also used to implement the bridge connections between external communications networks. The processor <b>30</b> knows the port addresses of each of the plurality of network interfaces <b>12</b>. Therefore, by appropriately controlling the hardware bus <b>34</b>, the processor <b>30</b> can establish any desired connection between network interfaces. As can be appreciated, the number of different connection configurations that can be implemented within the bridge <b>14</b> is only limited by the number of external networks that are coupled to the bridging apparatus <b>10</b>. In addition, because the bridging connections are established through software, the connections can be quickly and easily changed based on current system requirements. In this regard, the bridging apparatus of the present invention provides a level of bridging control that has not heretofore been realized.

In one embodiment of the present invention, at least some of the interface functionality is implemented in software within the same processor as the bridging functionality. That is, the processor stores some programs that are capable of performing bridging functions and some that are capable of performing interface functions. The processor then executes the different programs as needed. Other interface functions can be implemented outside of the processor using, for example, discrete digital or analog hardware elements. In one approach, discrete analog hardware elements (such as, for example, mixers, low noise amplifiers, and analog filters) are used to process a signal received from an external communications network. The resulting signal is then converted to digital form (in an analog-to-digital (A/D) converter, for example) before being delivered to the processor. The processor can then perform further interface functions on the signal, such as demodulation, decryption, error correction, and/or protocol conversion. The processor will know how to process a given signal based on the port through which the signal was received. In another approach, separate digital processors are used to perform the interface functions and the bridging functions. As can be appreciated, a number of other processing alternatives are also possible in accordance with the present invention.

In one aspect of the present invention, the plurality of network interfaces <b>12</b> includes at least one interface that is electronically reconfigurable. That is, the network interface can be reprogrammed in the field for changing, for example, the signal format supported by the interface. This feature is advantageous in situations where, for example, the signal format used by one of the external communications networks has been revised. In addition, this feature allows an old network to be quickly and easily replaced by a new network using a different signal format. If the network interfaces are wholly or partially software-based, reconfiguration can be as simple as changing the program being used to implement the interface. In another approach, field programmable gate arrays (FPGAs) are used to provide the desired reconfigurability. To be reconfigured, an FPGA generally requires a new configuration file to be delivered to an input of the unit. If a signal format change occurs in a particular external network, for example, a new configuration file can be delivered to a corresponding FPGA to maintain bridge compatibility with the external network. Other types of reconfigurable equipment may also be appropriate. A library of configuration files and/or interface programs can be maintained within the bridging apparatus <b>10</b> for use in configuring the plurality of network interfaces <b>12</b>.

FIG. 3 is a block diagram illustrating a multi-channel radio system <b>50</b> in accordance with one embodiment of the present invention. The multi-channel radio system <b>50</b> is capable of supporting radio communications between a user of the radio system <b>50</b> (located at user device <b>53</b>) and any one or more of a plurality of external wireless networks <b>52</b><i>a</i>-<b>52</b><i>n</i>. In addition, the multi-channel radio system <b>50</b> is capable of setting up bridging connections between external wireless networks <b>52</b><i>a</i>-<b>52</b><i>n </i>in accordance with system requirements.

As illustrated in FIG. 3, the radio system <b>50</b> includes: a plurality of radio channels <b>54</b>, a bridge <b>56</b>, and a user interface <b>58</b>. Each of the plurality of radio channels <b>54</b> is connected to an antenna for communication with one or more of the external wireless networks <b>52</b><i>a</i>-<b>52</b><i>n </i>via a corresponding wireless communications channel. For example, in the illustrated embodiment, radio channel <b>58</b><i>a </i>is coupled to antenna <b>60</b><i>a </i>for communication with wireless network <b>52</b><i>a </i>via wireless channel <b>62</b><i>a</i>; radio channel <b>58</b><i>b </i>is coupled to antenna <b>60</b><i>b </i>for communication with wireless network <b>52</b><i>b </i>via wireless channel <b>62</b><i>b</i>; and radio channel <b>58</b><i>n </i>is coupled to antenna <b>60</b><i>n </i>for communication with wireless network <b>52</b><i>n </i>via wireless channel <b>62</b><i>n</i>. It should be appreciated that other antenna arrangements, such as antenna sharing arrangements, can also be used in accordance with the present invention. In one embodiment, for example, a single array antenna having multiple fixed or independently steerable beams is utilized.

Each of the radio channels <b>58</b><i>a</i>-<b>58</b><i>n </i>comprises a radio transceiver capable of receiving/transmitting communications signals (from/to a corresponding wireless channel) having a signal format defined by a corresponding external wireless network <b>52</b><i>a</i>-<b>52</b><i>n</i>. The radio channels <b>58</b><i>a</i>-<b>58</b><i>n </i>are each capable of converting a received signal into a baseband data representation for delivery to the bridge <b>56</b>. Likewise, the radio channels <b>58</b><i>a</i>-<b>58</b><i>n </i>are each capable of converting a baseband data signal received from the bridge <b>56</b> into an appropriate transmit signal format for delivery to a corresponding external communications network <b>52</b><i>a</i>-<b>52</b><i>n</i>. Each of the radio channels <b>58</b><i>a</i>-<b>58</b><i>n </i>can be configured for use with a different wireless signal format or two or more (or all) can be adapted for use with the same wireless signal format. The radio channels <b>58</b><i>a</i>-<b>58</b><i>n </i>can include, for example, off-the-shelf radio slices that can be plugged directly into an expansion slot on a hardware bus. Alternatively, one or more of the radio channels <b>58</b><i>a</i>-<b>58</b><i>n </i>can be implemented using an FPGA, or other reconfigurable resource. Likewise, some or all of each radio channel can be implemented in software. In addition, standard hardware implementations can be utilized.

The bridge <b>56</b> performs substantially the same functions as the bridge <b>14</b> of FIG. <b>1</b>. That is, the bridge <b>56</b> establishes at least one bridge connection between external wireless networks <b>52</b><i>a</i>-<b>52</b><i>n</i>. In addition, the bridge <b>56</b> can establish communications connections between the user device <b>53</b> and any one or more of the external wireless networks <b>52</b><i>a</i>-<b>52</b><i>n</i>. As before, the functionality of the bridge <b>56</b> is implemented in software within a digital processor. Also as before, the bridge <b>56</b> can receive configuration commands and/or bridging programs from a user via user interface <b>58</b>.

In a preferred embodiment, the plurality of radio channels <b>54</b>, the bridge <b>56</b>, and the user interface <b>58</b> are all included within a single box. That is, the elements are all supported by a single support structure, such as a radio housing. By including the bridging functionality within the same box as the radio equipment, the efficiency of data delivery between external networks can be significantly increased. In addition, the “single box” approach allows complex control by a user of the radio system <b>50</b>. The radio system <b>50</b> of the present invention can be implemented in, for example, (i) a rack mountable housing for use in basestation and/or other stationary applications or (ii) a relatively compact, portable housing for use in mobile applications. In one embodiment, a handheld, multi-channel bridging radio is provided. Other implementations, such as those involving marine and/or airborne applications, also exist.